Electrically detected magnetic resonance

Electrically detected magnetic resonance (EDMR) is a very sensitive technique, which can be used for the spectroscopic characterisation of photovoltaic materials on the nanoscale. We have studied the most important recombination centres in Czochralski silicon (Cz-Si) containing strained oxide precipitates (OPs) with a wide range of densities. Cz-Si is used for the vast majority of silicon integrated circuits and ~40% of solar cells, and is known to suffer from various impurities. Strained OPs reveal a square platelet-like shape and are used to confine detrimental impurities to inactive regions of the wafer in a process called internal gettering. The recombination centres associated with intentionally grown OPs as well as with iron-related impurities, such as interstitial iron and the iron-boron pair, are identified via EDMR and discussed. Our results demonstrate that OPs are associated with Pb0 and Pb1 dangling bonds forming at the corners of those platelets.

Electrically Detected Magnetic Resonance at High Magnetic Fields

We have investigated the EDMR effect in silicon field-effect transistors (FETs) and demonstrate the readout of arsenic and phosphorus donor spins in a resonant microwave cavity at 3.36 T and 94 GHz (W-band) for the first time worldwide. A comparison between conventional low- and high-field EDMR on the same devices shows that bolometric heating as well as spin-dependent scattering can be ruled out as the underlying mechanism giving rise to the spin resonance signals in FETs. Our signals are rather understood in terms of a polarisation transfer from the donor to the two-dimensional electron gas forming in the device channel.